Many facilities, such as restaurants, have production processes which require the discharge of high volumes of grease through roof-mounted discharge vents. The discharged grease may accumulate on the roof and cause deterioration of the roofing materials surrounding the grease discharge vent, including the flashing and gaskets associated with the vent installation. These roofing materials are typically organic materials which may deteriorate rapidly when exposed to grease. Various filters and grease traps disposed between the grease generating source and the discharge vent have been used to reduce the quantity of airborne grease discharged from the discharge vent. However, such devices have been unsuccessful in absorbing or trapping all of the grease, and even when such filters are employed, a significant amount of grease is still discharged from the discharge vent and onto the roof. Thus, there is a need for a filter assembly for absorbing or trapping grease discharged from roof-mounted discharge vents.
One such filter assembly is disclosed in U. S. Pat. No. 5,196,040 entitled "Grease Trap and Filter Apparatus". This patent discloses a frame structure which is mounted directly to the roof through which the discharge vent projects. Grease absorbing material has a central portion cut out corresponding to the specific shape of the discharge vent. The grease absorbing material is disposed inwardly of the roof-mounted frame structure, surrounding the discharge vent. This roof-mounted design suffers numerous shortcomings. Among the shortcomings associated with the patented roof-mounted design is that the frame structure is mounted directly to the roof. While the roof-mounted frame may be suitable for those applications in which the roof section immediately surrounding the discharge vent is flat and extends substantially perpendicularly with respect to the discharge vent extending therefrom, the roof-mounted frame does not lend itself to use in the wide variety of applications in which the roof section surrounding the discharge vent is angled with respect to the discharge vent extending from the roof section. There is a need for a filter assembly which is well suited for any type of roof surface or roof configuration.
Another shortcoming associated with the roof-mounted frame structure of the patented design is that it is not suitable for use with tall discharge vents which extend a substantial distance from the roof. The roof-mounted frame structure may be disposed too far away from the high, grease discharging end of the discharge vent to catch the airborne grease before it blows beyond the confines of the frame structure and onto the roof. There is a need for a filter assembly which catches grease discharged from a discharge vent regardless of the height which the discharge vent extends from the roof.
A still further shortcoming associated with the aforementioned patented device is the requirement that the grease absorbing material be cut specifically for each different application to correspond to the particular shape of that specific discharge vent. That is, the grease absorbing material is disposed inwardly of the frame structure and between the frame structure and the discharge vent, requiring that the grease absorbing material be cut accurately to fit snugly between the frame and the periphery of the discharge vent. There is a need for a filter assembly which lends itself to use with discharge vents of a wide variety of shapes and sizes, without requiring cutting of the grease absorbing material to correspond to each separate specific shape and sizes.
Moreover, the aforementioned patented device requires screwing or nailing flashing onto the discharge vent duct itself to properly secure the grease absorbing device in place. Many municipal codes prohibit screwing into the duct stack. Therefore, there is a need for a grease filter device which is mountable to a grease discharge vent in a secure, stationary position while maintaining the integrity of the discharge vent duct.
There is a need for a filter assembly which overcomes each of the aforementioned shortcomings of the prior art construction, and which also lends itself to inexpensive production and allows for easy removal and replacement of used grease absorbing materials.